January 24th, 2016 29,245
Upgrading to a minor version is done through the upgrade process of Debian. For major versions, the process is much more complex.
How to Install PostgreSQL 9.1 or the latest PostgreSQL version 9.3 on Debian 7 Wheezy. Basic settings after installation.
October 21st, 2013 286,544
Logs is the best place to start troubleshooting. Concerning MySQL (or MariaDB), you need to refer to: General query Log, Error Log and Slow Query Log
Recently, many popular Linux distributions have moved from MySQL to MariaDB. Think if you have to move to MariaDB in your production servers.
PHP MySQL extension is deprecated. PHP MySQLi extension is Object Oriented, supports Transactions and protects from SQL Injection, using Prepared Statements.
Using php ADODB database abstraction layer, you can create PHP applications, which are functioning with many databases without modification to source code.
Using MySQL command line client and mysqldump to perform the most important tasks for everyday use, every administrator or web developer needs to know.